The present invention relates to magnetic heads for use in a disc drive, and more particularly to a reader of a magnetic head.
A magnetic head of a magnetic data storage and retrieval system typically includes a reader portion for retrieving magnetic data stored on a magnetic medium. The reader is typically formed of several layers, which include a sensor, positioned between two insulating layers, which are in turn positioned between two shield layers. The sensor may be any one of a plurality of magnetoresistive (MR) type sensors, including anisotropic magnetoresistive (AMR), giant magnetoresistive (GMR), tunneling giant magnetoresistive (TMR), spin valve, and spin tunneling sensors. When the magnetic head is placed near the magnetic medium, a resistance of the sensor fluctuates in response to a magnetic field eminating from within transitions in the magnetic medium. By providing a sense current through the sensor, the resistance of the sensor can be measured and used by external circuitry to decipher the information stored on the magnetic medium.
One of the crucial steps in the formation of a reader of a magnetic head is the definition of the sensor stripe height. The stripe height is the distance between the front edge (defined as the air bearing surface) of the sensor and the back edge of the sensor. Prior art methods of forming the reader have experienced problems during the definition of the sensor stripe height. One of these problems occurs from a shadowing effect from the relatively thick photoresist layer that is used to mask the sensor. While the unmasked portions of the sensor are being removed, a shadow cast by the photoresist layer causes a tail to form on the back edge of the sensor. This tail, which extends backward from the back edge of the sensor along the surface of a first half gap results in a reduction of the sensitivity of the MR sensor. A second problem experienced by the prior art is the formation of redeposition material along the back edge of the photoresist layer. Even after the photoresist layer is removed the redeposition material remains on portions of the sensor device, which can result in unwanted electrical connections and a defect in the magnetic head's topography. A third problem that occurs in the prior art results from attempts to remove the redeposition material from the reader. While these processes can remove some of the redeposition material, the harsh redeposition removal processes can cause damage to other portions of the reader, or damage adjacent devices formed on the same wafer.
Therefore, there is a need in the art for a method of forming a reader of a magnetic head having a sensor formed with a steep back edge that does not form unwanted redeposition material or damage other features of the wafer.